longtermeffect of vol eruption

(1) Large, explosive volcanic eruptions inject H2O, CO2, SO2, HCl, HF and ash (pulverized rock and pumice) into the stratosphere.
(2) The conversion of SO2 to H2SO4, which condenses rapidly in the stratosphere to form fine sulfate aerosols. The aerosols increase the Earth's albedo—its reflection of radiation from the Sun back into space - and thus cool the Earth's lower atmosphere or troposphere;
(3) however, they also absorb heat radiated up from the Earth, thereby warming the stratosphere.
(4)Several eruptions during the past century have caused a decline in the average temperature at the Earth's surface of up to half a degree (Fahrenheit scale) for periods of one to three years — SO2 from the eruption of Huaynaputina probably caused the Russian famine of 1601 - 1603.
(5)Promote complex chemical reactions that alter chlorine and nitrogen chemical species in the stratosphere. This effect, together with increased stratospheric chlorine levels from chlorofluorocarbon pollution, generates chlorine monoxide (ClO), which destroys ozone (O3).
(6) Serve as nuclei for cirrus clouds and further modify the Earth's radiation balance.
(7) Most of the HCl and hydrogen fluoride (HF) are dissolved in water droplets in the eruption cloud and quickly fall to the ground as acid rain.
(8) Release the greenhouse gas carbon dioxide and thus provide a deep source of carbon for biogeochemical cycles.
(9) Volcanic activity releases about 130 to 230 teragrams (145 million to 255 million short tons) of CO2 each year. Large injections may cause visual effects such as unusually colorful sunsets and affect global climate mainly by cooling it.
(10) Provide the benefit of adding nutrients to soil through the weathering process of volcanic rocks. These fertile soils assist the growth of plants and various crops.
(11) Create new islands, as the magma cools and solidifies upon contact with the water.

2009-04-04 02:54:46 補充：
(12) Eruption brings heavy minerals such as gold to reconcentrate near the ground surface.

2009-04-04 02:56:51 補充：
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